diff --git a/modules/demux/mkv/matroska_segment.cpp b/modules/demux/mkv/matroska_segment.cpp
index 9fa07f0a3d21f05f1f22618cd90223c89162573b..2a7d0853a24aeae41620aa3ba5c951f5bd502f46 100644
--- a/modules/demux/mkv/matroska_segment.cpp
+++ b/modules/demux/mkv/matroska_segment.cpp
@@ -1407,7 +1407,7 @@ int matroska_segment_c::BlockGet( KaxBlock * & pp_block, KaxSimpleBlock * & pp_s
 
                 ref.ReadData( es.I_O() );
 
-                if( int64( ref ) < 0 )
+                if( *pb_key_picture )
                     *pb_key_picture = false;
                 else if( int64( ref ) > 0 )
                     *pb_discardable_picture = true;